This invention relates to an adjustable support, and more particularly, to a support for a chair or stool which is adjustable to vary the height of the seat thereof.
For a number of years a pneumatically-operated piston-and-cylinder unit has been employed in many chairs of the pedestal type, serving both as the load-bearing member between the base and the seat of the chair and as a means for adjusting the height of the seat relative to the base in response to manual actuation of a lever or handle located directly beneath the seat so that it is readily accessible to an occupant of the chair.
In such supports, the magnitude of the internal pneumatic pressure is so selected that when the handle is actuated and the seat is occupied, the weight of the occupant acts to reduce the height of the pneumatic unit and thus of the seat. When the handle is actuated and the seat is unoccupied, the height is increased as a result of the action of the virtually unopposed pneumatic pressure.
Such units are not only easily operated, they are comfortable in operation because of the buffering effect of the compressed gas which provides the pneumatic pressure. However, they are relatively expensive, and no matter how well they are made, wear and aging of the pneumatic seals sooner or later permits the gas to escape, and eventually the unit or the chair itself must be replaced.
The present invention is intended to provide a mechanical, as opposed to pneumatic, substitute or replacement for such a unit at lower cost but with the same ease of operation, similar comfort, and substantially identical exterior configuration.
Supports which may be selectively fixed at various predetermined heights have long been known. An early example is the piano stool disclosed in U.S. Pat. No. 316,281, issued Apr. 21, 1885, to W. A. C. Matthie. Here the seat of the stool is supported on a vertically extending spindle. Formed in the outer surface of the spindle are a number of annular recesses in parallel, vertically spaced relation to each other. A tubular base or stand telescopically receives the lower end of the spindle. Also contained within the stand is a spring biasing the spindle upwardly relative to the stand. Detent means supported on the stand are receivable in any one of the recesses to lock the spindle in a respective one of a plurality of vertical positions relative to the stand. Actuating means are operable to withdraw the detent means from one of the recesses to permit movement of the spindle vertically relative to the stand. The actuating means extends laterally outwardly from the stand at a fixed height, whereby the distance from the seat to the actuating means is variable.
Also representative of the prior art is the stool disclosed in U.S. Pat. No. 2,780,277, issued Feb. 5, 1957, to E. J. Ries et al. Here, too, the seat of the stool is supported on a vertically extending spindle in the outer surface of which are formed a plurality of annular recesses in parallel vertically spaced relation. Again, the spindle is telescopically received in a tubular base. A locking device comprises a collar rigidly secured to the upper end of the support and detent means pivotally mounted in the collar to be received in one of the recesses, whereby to lock the spindle in a respective vertical position relative to the support. In this instance, the detent actuating means is operated by means of a release bar disposed at the lower end of the support for engagement by the foot of the occupant of the seat, thereby freeing his hands.